Pulmonary embolism is a recognized medical emergency, and is often caused by venous thrombosis. Physiological conditions such as venous intima damage, blood flow retention, and coagulation abnormalities are often the cause of venous thrombosis. Recognized treatments for venous thrombosis include anti-coagulant medication therapy, thrombolytic therapy, thrombectomy, and inferior vena cava thrombosis filtering or blocking procedures.
When an inferior vena cava thrombosis filtering or blocking procedure is selected, it can be performed using either a laparotomy procedure, or by percutaneously inserting a thrombosis filter. A laparotomy procedure is a surgical procedure performed under general anesthesia. Because it is necessary to discontinue anti-coagulant therapy prior to surgery, this procedure, itself, is susceptible to thrombosis formation.
The second option is to intravenously insert a thrombosis filter into the vascular system. In particular, the thrombosis filter is mounted into the inferior vena cava in order to prevent large emboli from passing to the lungs. Since this procedure requires only a local anesthetic, percutaneous filter insertion is recognized as an effecateous procedure. Thrombosis filters, however, become encapsulated to the vein wall through neointimal hyperplasia. Neointimal hyperplasia is the subsequent increase in endothelial cell production caused by the irritation of the lining membrane of the blood vessel. Neointima grows from the inner wall of the blood vessel, around the thrombosis filter and its anchors. This process can occur within two or three weeks after implantation, rendering many thrombosis filters unremovable by a single percutaneous process without significant vessel trauma.